Whether you live in an apartment or a house ten feet from another, it's important to make sure that sound levels coming from your home aren't going to result in trouble from the neighbors. But don't fret, as there are simple ways for you to tweak your sound to maximize the experience without affecting your neighbors, all of which are explained here.

Okay I had to add something more. First of all I loved your write up of this concept of being able to hear everything you want without blowing your eardrums out or disrupting the neighbors. This is something that simply gets ignored yet it's very important.

Another way one can add to your idea of AC3filtering is you can place the speakers that you're listening to as close to the listener(s) as possible. Boy does this make a difference in how loud you need to play it in the first place: Halving the distance probably gives you a good 25% boost in volume with the same Neighbor Disruption Factor (NDF). Especially the subwoofer! OMG if you do yourself the favor of placing the subwoofer literally underneath your chair or couch, holy smokes, get ready for a treat. Again this lowers the NDF by a huge amound. Another thing that you can do, is be seated on something as firm as possible. This is because the firmer the surface is that is touching your skin, the more energy is passed from the speakers directly to the nerves all throughout your skin and you really "feel" the sound. Think of when you are sitting in a car, preferebly with a decent stereo system, and you are listening, while parked, with your left arm making contact with the armrest in the door. Notice how you can feel not just the bass but the midrange too? Well imagine this feeling over the whole half of your body which is sitting in front of your movie screen.

Okay I had to add something more. First of all I loved your write up of this concept of being able to hear everything you want without blowing your eardrums out or disrupting the neighbors. This is something that simply gets ignored yet it's very important.

I'm glad you liked my little "how to". One of the benefits of this setup is that without sacrificing much in the way of dynamics and enjoyment, the movie is actually much louder... Which lets you turn the volume down, reducing the risk of wall penetration and the resulting annoyance to your neighbors.

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Another way one can add to your idea of AC3filtering is you can place the speakers that you're listening to as close to the listener(s) as possible.

Yes that does increase the apparent volume by quite some measure.

However, I would caution you that speaker placement is an important consideration in home theatre setups. 4.1, 5.1 (and beyond) sound creates a positional image in which sounds are positioned 2 dimensionally within the boundaries of your speaker layout. Getting the speakers too close seriously reduces this aspect of your soundscape as there is no longer an adequate directonal cue from the speakers.

One crucial aspect of placement is the sub-woofer, as you point out. My general recommendation is that whenever possible it should be a down firing design located right in the middle of the listening area. Sounds at thes frequencies (pitch) are very non-directional and tend to fill a room. This makes the center of the room the most rational place to source them.

Of course you never want to place your sub-woofer on an outside wall, if you can help it. That's just begging for complaints from neighbors... especially in apartments.

Another issue that most people miss is that most sub woofer enclosures are vented, often by a big gaping hole... This wants some thought... As the speaker cone moves out it is producing pressure in the room... but the back of it tends to produce a vaccum in the speaker cabinet. If the port is large enough, compared to the frequency, air can actually flow back and forth very freely. The result is a pressure wave from the front of the speaker being cancelled by the reverse aiflow into the port towards the back of the speaker. The result is actual cancellation of sound... not the "big bass" manufacturers claim. In fact, many actually put ports in their boxes only because customers expect them... not because they make accoustic good sense.

The very best bass is always achieved from an "Infinite Baffle" (Sealed) enclosure. This contains the reverse pressure of the back of the speaker inside the enclosure where it's not going to affect the front wave. It also has a damping effect on the speaker itself giving you much less "rubbery" sounding bass. (i.e. Thud is Thud... not BOOOM)

A simple experiment... Stuff a sock in it! Really... to get increased low bass, with less power (and thus less chance of wall penetration) try blocking the bass port in your subwoofer. You might be pleasantly surprised. My listening room is about 12 by 14 and I get absolutely excellent bass from a 4" sub-woofer running on about 20 watts, of which I'd bet I'm using less than 10.